It wasn’t supposed to be Justin Trudeau’s night. International affairs are his Achilles’ heel, the subject on which he cracks inappropriate jokes, expresses admiration for dictatorships and supports legislation that makes progressives cringe.

The Munk Debate on foreign policy loomed on the election calendar like … that boxing match three years ago with the now-disgraced Senator Patrick Brazeau. Which might have been our first clue that it wasn’t going to go quite as expected.

And it didn’t. Put it down to low expectations, serious preparation, sheer determination, or some combination of the three: Trudeau he held his own, and then some. You might think he’s completely out to lunch when defending the right of convicted terrorists to keep their citizenship. You might roll your eyes when he explains why he voted in favour of Bill C-51. You might scoff when he talks of plowing billions of dollars of borrowed money into shipbulding.

But even if you disagree vehemently with his positions, you couldn’t deny that he delivered them with conviction. Throughout the night, he clearly articulated Liberal policies, defended them passionately, threw in some good zingers (describing Stephen Harper’s northern strategy as “all sled, no dogs”) and, most importantly, didn’t trip up. And so, Trudeau won last night’s debate.

Stephen Harper delivered a solid, deadpan, confident performance befitting that of a senior statesman. He frequently reminded the audience that, unlike his two rivals, he actually has experience in foreign affairs — meeting with Vladimir Putin, visiting Syrian refugees camps, travelling to Ukraine and negotiating international trade deals. When NDP leader Thomas Mulcair concluded the debate by asking who Canadians want to see sitting down with Angela Merkel, Harper was the only one of the three leaders one could easily picture in that role, in part because he’s already there.

The Conservatives know that their best chance at remaining in power lies is sowing doubt about the alternatives, and having the Liberals and NDP do the job for them is even more effective.

When Harper’s rivals questioned his record, the Conservative leader methodically dismantled their arguments, attacked the records of their parties, and gave no quarter. From repudiating Kyoto to defending Israel to not funding abortion overseas, Harper remained straightforward and sure. He even managed to deliver the debate’s funniest moment: When Trudeau accused Harper of trading on fear, of seeing ISIS lurking behind every rock and tree, Harper looked under his lectern, prompting gales of laughter from the audience. Trudeau’s surefootedness impressed because it was unexpected; Harper’s moment of wit did the same thing, for the same reason.

Which leaves Mulcair. He had the trickiest job of the night: recapturing the momentum that has shifted away from the NDP, and repositioning himself as the anti-Harper in the minds of progressive voters. To do that, he had to give a bravura performance; while his offering was earnest and credible, it was not enough. Mulcair simply did not bring the same energy as Trudeau did on matters such as bringing in more refugees, or reclaiming Canada’s status as an environmental leader. He also trotted out tired chestnuts such as “rip and ship”, and tried to score points when they were clearly not coming, such as repeatedly pressing Harper on protecting the totality of the supply management system.

To be fair, Mulcair did deliver many good lines — reminding the audience that deficit-loving Premier Bob Rae was a Liberal, admonishing Trudeau for supporting the Tories’ anti-terror legislation (“How will you stand up to Putin if you can’s even stand up to Harper on Bill C-51?”).

Sometimes his attacks backfired. When Mulcair invoked Pierre Trudeau’s jailing of hundreds of suspected FLQ terrorists during the October Crisis, Trudeau shot back with a spirited defence of his father’s legacy on human rights, including the adoption of the Charter of Rights and Freedoms, and finished with this: “Fifteen years ago tonight he passed away, and he wouldn’t want us fighting battles of the past.” Ouch. Later, when Trudeau accused Mulcair of making pompous statements, Mulcair shot back, “I’ll leave the pomp to you Justin”. Despite eliciting some hearty guffaws, the retort made Mulcair sound snippy — not a quality voters tend to admire in their politicians.

Perhaps this explains why Harper looked so relaxed last night; foreign policy is his favorite topic and the one-on-one format of the debate allowed him several occasions to just sit back and watch his rivals tear each other apart. The Conservatives know that their best chance at remaining in power lies is sowing doubt about the alternatives, and having the Liberals and NDP do the job for them is even more effective.

The trick, however, will be to maintain enough of a vote-split so that neither of the other parties can form a government. With three weeks and one more debate to go, it’s an open question whether they can pull it off — especially if Trudeau surprises again.

Tasha Kheiriddin is a political writer and broadcaster who frequently comments in both English and French. After practising law and a stint in the government of Mike Harris, Tasha became the Ontario director of the Canadian Taxpayers Federation and co-wrote the 2005 bestseller, Rescuing Canada’s Right: Blueprint for a Conservative Revolution. Tasha moved back to Montreal in 2006 and served as vice-president of the Montreal Economic Institute, and later director for Quebec of the Fraser Institute, while also lecturing on conservative politics at McGill University. Tasha now lives in Whitby, Ontario with her daughter Zara, born in 2009.

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